1. Field of the Invention
The present invention relates to a reference voltage circuit which outputs a reference voltage excellent in temperature characteristic.
2. Background Art
A related art reference voltage circuit will be described. FIG. 6 is a circuit diagram illustrating the related art reference voltage circuit.
The related art reference voltage circuit is equipped with an NMOS depletion transistor 601, an NMOS transistor 602, a ground terminal 100, an output terminal 102, and a power supply terminal 101.
In the related art reference voltage circuit, a gate and source of the NMOS depletion transistor 601 are connected to each other, and a gate and drain of the NMOS transistor 602 are connected to each other. They are connected in series and a connecting point therebetween is defined as the output terminal.
The related art reference voltage circuit uses the NMOS depletion transistor 601 as a constant current source and extracts a voltage generated in the NMOS transistor 602 as a reference voltage Vref. As the reference voltage Vref, the sum of an absolute value Vtnd of a threshold voltage of the NMOS depletion transistor 601 and a threshold voltage Vtne of the NMOS transistor 602 is outputted (refer to, for example, FIG. 10 in Patent Document 1).